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V polšaržnem reaktorju smo izvedli poskuse vezave plinastega CO2 v različne raztopine Ca(OH)2. Določili smo ponovljivost in izkoristek reakcije s čistim kalcijevim hidroksidom in karbidnim apnom ter analizirali fizikalne lastnosti končnega produkta. Zasnovali smo matematični model za opis kinetike reakcije in snovnega prenosa. Pri poskusih z dimnimi plini smo spreminjali ekspozicijske čase in na osnovi teh določili izkoristek reakcije glede na čas uvajanja plina. Za analizo produkta smo izbrali lastnosti, ki so definirane pri komercialnih izdelkih, in jih primerjali. Analizirali smo pH, nasipno gostoto, vlažnost in vsebnost železa. Podrobno smo preučili reakcijski mehanizem in določili prevladujoče ravnotežne reakcije. Spremljali smo spremembo koncentracij hidroksidnih, kalcijevih, karbonatnih in hidrogenkarbonatnih ionov v raztopini. Za definiranje mehanizma so se za ključne izkazali hidroksidni, kalcijevi in hidrogenkarbonatni ioni. Pomemben parameter je tudi pH, ki ima za dano reakcijo karakteristično krivuljo in definira začetek in konec celokupne reakcije. Procesni parametri, ki so imeli največji vpliv na reakcijo, so: volumen raztopine, pretok in koncentracija plina ter intenziteta mešanja. Za intenzifikacijo procesa bo potrebna podrobnejša analiza kinetike reakcije in vpletenih transportnih pojavov predvsem v smislu določevanja konstant reakcijskih hitrosti in koeficientov snovnega prenosa. Experiments on the binding of gaseous CO2 to different Ca(OH)2 solutions were carried out in a semi-batch reactor. The reproducibility and the yield of the reaction with pure calcium hydroxide and carbide lime were determined. An analysis of the physical properties of the final product was performed. We designed a mathematical model to describe the reaction kinetics and the mass transfer phenomena involved. In experiments with flue gases, the exposure times varied and the results were used to determine the absorption. For product analysis, we selected and compared the properties of commercially available products. We analysed pH, bulk density, moisture content and iron content. We studied the reaction mechanism in detail and determined the predominant equilibrium reactions. We observed the change in concentrations of hydroxide, calcium, carbonate and bicarbonate ions in the solution. Hydroxide, calcium and bicarbonate ions proved to be key in determining the mechanism. An important parameter is the pH of the solution, which has a characteristic curve as a function of time and determines the beginning and end of the whole reaction. The process parameters that had the greatest influence on the reaction were the volume of the solution, the gas flow and concentration and the intensity of mixing. To intensify the process, a more detailed analysis of the reaction kinetics and the transport phenomena involved is required. This in particular applies to the determination of the reaction rate constants and the mass transfer coefficients. |
